Re: Kernel 2.6.30rc7 limits IDE to UDMA33

["Michael S. Zick" <lkml@morethan.org>]

On Sun June 7 2009, Grozdan wrote:
> 2009/6/7 Robert Hancock <hancockrwd@gmail.com>:
> > Grozdan wrote:
> >>
> >> 2009/6/6 Robert Hancock <hancockrwd@gmail.com>:
> >>>
> >>> Thing is somehow the GTM detection isn't working now and it apparently
> >>> was
> >>> in 2.6.27.1. I'm not seeing any patches to pata_via or libata-acpi that
> >>> seem
> >>> like they would affect this offhand. Grozdan, would you be able to try
> >>> git
> >>> bisect to try to figure out what changed the behavior?
> >>>
> >>> CCing Tejun in case he has any ideas..
> >>>
> >>
> >> I've no idea how and where to do a git bisect so if someone is willing
> >> to explain in simple steps, I can try...
> >
> > Linus's post on here is a pretty simple explanation:
> >
> > http://kerneltrap.org/node/11753
> >
> 
> Yes, it's clear to someone who's familiar with git but not to a noob
> like me. Where do I run this git? After it's finished what to do next?
> How many times do I have to compile kernels? Which kernels exactly?
> After booting a "bad" kernel, what then? etc... From reading the
> article, the guy has to compile 14!! times just to catch a problem
> between kernel 2.6.21 and 2.6.22. 
>

The article presumes the simple case of a single commit being the
problem.  If the problem involves more than one. . .

Think of doing a binary search in a list of values with duplicate
entries.  ;)

> I guess in my case I'll have to 
> compile a lot more than 14 times to catch something between kernel
> 2.6.27 and 2.6.30 and honestly I don't have time for this right now.
>

Yes, it can get to be time-consuming unless your lucky.

> However, I did a diff between the pata_via driver of kernel 2.6.27 and
> 2.6.30 and there have been changes to it but I'm not sure if they
> affect the cable detection...
>

That's a start.  Now if you knew what you where looking for...
(No offense intended - "diff" doesn't place "here I am" markers.)

The machine I am doing my own tests on uses the pata_via driver and
it detects the udma66 disk drive as a udma33 - - -

But finding this is way down on my list of things to look for -
Someone else is welcome to beat me to it.

Mike
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